Efficient removal and recovery of lead from high arsenic antimony oxide powder

The existence of Pb in crude antimony oxide powder(CAOP) hinders the further smelting and recovery of Sb and leads to some environmental problems. Therefore, the selective removal of Pb from CAOP is important for the production of high-purity antimony products. In this work, Pb in CAOP is removed by HNO₃ leaching, achieving purification of CAOP. Then H₂SO₄ is used to recover Pb from the HNO₃ leaching solution. The Pb leaching efficiency reaches 98.9 %, resulting in a decrease in the Pb content from 4.56 % to 0.20 % in CAOP. The Sb leaching efficiency is controlled at around 5.0 %. These confirm HNO₃ has good selectivity. The HNO₃ disrupts the molecular structure of the raw materials during the leaching, resulting in the conversion of Sb₂O₃ and As₂O₃ into insoluble AsSbO₄. By adding H₂SO₄ to the leaching solution, the Pb precipitation efficiency reaches 93.6 %. After Pb removal, the leaching solution can be re-used for the leaching of Pb, while the residue can be directly returned to the pyrometallurgical system. The reaction mechanism and a novel approach for removing Pb from CAOP are proposed, which have the advantages of high selectivity, effective Pb separation, and recoverable HNO₃.